Brazil's state-owned energy giant Petrobras says it has started oil production at a deep-water well off the coastal state of Espirito Santo.
Oil began flowing on Monday at a floating platform located in the Baleia Azul field, 80km off the coast, the company said.
The area is part of Brazil's large "pre-salt" offshore reserves discovered in 2006 that are buried beneath ocean, bedrock and hot salt beds.
The statement said initial production from the existing well is estimated at 20,000 barrels per day, with peak output of 100,000 barrels per day expected by February 2013.
Brazil, the world's sixth largest economy, hopes to boost its oil production from a current two million barrels a day to nearly five million by 2020.
The National Petroleum Agency estimates that the "pre-salt" reserves could hold more than 100 billion barrels of high-quality recoverable crude and could turn Brazil into one of the world's top exporters.
Less than 10 per cent of oil production currently originates in the "pre-salt" layer.